RPM's in and out of gear

Thumpbass

Petty Officer 2nd Class
Joined
Jul 23, 2006
Messages
197
I have a '79 100hp Johnson. I read in my manual and on the board that I should be idling in the 650 range in gear and closer to1000 out of gear. As it stands right now my motor is idling at the same rpm's whether it's in gear or neutral...in other words if the throttle cable is adjusted to idle at 1500 rpm's when I shift into forward the rps don't drop or change...if the throttle cable is set to idle at 650 in neutral it stays at 650 when I shift into forward as well. All of this is done while the motor is on the muffs....is this right or should the rpm's be dropping when I shift into gear?
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: RPM's in and out of gear

That's pretty much how mine is. No real difference in or out of gear..I think you're ok...You should see a bit of difference on the water due to back pressure on the exhaust...Set it in gear on the water and you're good to go...
 

Thumpbass

Petty Officer 2nd Class
Joined
Jul 23, 2006
Messages
197
Re: RPM's in and out of gear

so you think I should just adjust the throttle cable to where it idles around 650 and go with it? I have only had the boat out a few times since I bought it so I'm trying to get it "tweaked"...when I got it the throttle cable was adjusted so that the motor was idling in and out of gear at 1000-1500 rpms...the shift cable was adjusted to where the rubber cap on the screw was no where near the idle stop. I just re-adjusted the cable so that the rubber is making caontact with the stop and that put it at 650...so with that being said will I still be able to get the same WOT rpms (5000-5500) with the throttle lever all the way forward...in other words do I need to do any other "link and sync" type stuff to compensate for the throttle cable adjustment (that allowed the lower idling)?
Seems fine on the muffs but I'm going night fishing tomrrow night and don't want to be making motor adjustments in the dark:|
 

Thumpbass

Petty Officer 2nd Class
Joined
Jul 23, 2006
Messages
197
Re: RPM's in and out of gear

"the shift cable was adjusted to where the rubber cap on the screw was no where near the idle stop"

meant to say throttle cable
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: RPM's in and out of gear

In gear or out of gear makes no difference in rpm when running on muffs. It is a different story when in the water because of the resistance of the propeller in the water as it attempts to push the boat. More simply, in the water it is doing work--pushing the boat--which puts a load on the motor, slowing it down. Put it in the water and adjust the idle in gear rpm to specs and forget it.
 
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